1. Field of the Invention
This invention relates to a method of provisioning a route in a connectionless communications network such that a guaranteed quality of service is provided. The invention is particularly related to, but in no way limited to, a method of provisioning a leased line in an internet protocol communications network.
2. Description of the Prior Art
A leased line is a route in a communications network between two points which are usually access points to the communications network or alternatively terminals or any other network nodes. The line is provided for use by a customer under a contract such as a service level agreement (SLA) under which the network operator agrees to provide use of the line with a guaranteed quality of service and bandwidth. A customer such as a company or enterprise may have two sites and wish to communicate between these two sites quickly and with a guaranteed quality of service. In this case, the customer can arrange with a network provider to have a leased line between those two sites. Such leased lines have been provided using switched or provisioned connections across connection oriented networks such as TDM (time division multiplex), ATM (asynchronous transfer mode) and Frame Relay networks. These types of communications networks are suitable for providing leased lines because it is relatively easy to set up a specific route across the network which has a guaranteed bandwidth and quality of service. In contrast, internet protocol communications networks are inherently connectionless and it is not straight forward to provide guaranteed quality of service and bandwidth over a specific route as is required for a leased line. For example, a packet routed over an internet protocol communications network is not routed over a pre-specified path but rather its actual path over the network will vary depending on particular network conditions at the time. However, with the advent of internet protocol communications networks such as the internet it is required to provide leased lines over internet protocol communications networks.
The IETF has defined mechanisms such as Differentiated Services (DiffServ) in order to address the challenge of connectionless internet protocol networks. However, Differentiated Services alone do not allow a specified quality of service to be guaranteed.
Multi-protocol label switching (MPLS) is currently being developed by the IETF in order to allow traffic routes in internet protocol communications networks to be pre-specified such that traffic may be routed over or “pinned to” specified paths. However, MPLS does not fully address the problem of providing guaranteed quality of service using an internet protocol communications network. In the same way, tag switching, which has been implemented to “pin” traffic routes, does not fully allow guaranteed levels of quality of service to be provided.
Service providers such as Internet Service Providers (ISPs) and other communications service providers are faced with increasing management problems as use of their services becomes more popular. Service level agreements (SLAs) are typically drawn up between a customer such as an enterprise, and a service provider and these SLAs set out the definitions of the service that the provider agrees to give. SLAs are traditionally paper contracts which list conditions such as quality of service levels and time periods over which services are to be provided, as well as detailing penalties which apply in the event that the agreed service levels are not met. These conditions are typically complex and detailed. Such SLAs arise in many situations, for example, between an access network provider and a service provider, between a service provider and a network provider and between two service providers. Also, a given service provider will have many SLAs for different customers and indeed may have many SLAs for each customer. The SLAs contain valuable information which is essential to the service provider or network operator for good network management and service management. However, obtaining this information quickly in a useable form is a difficult task.
Service providers also seek to provide differentiated services such as premium rate services and best effort services. In order to do this the service provider typically defines specifications for particular classes of service. By providing different classes of service a provider is able to promote greater use of its services whilst at the same time providing more choice for customers. However, once different classes of service are created, the management task for the service provider is increased in complexity.
Many service providers currently capture their SLAs and class of service specifications in documents created using standard word processing tools. However, this approach does not facilitate quick retrieval of information from the SLA and class of service documents in useable forms.
Two products, CrossKeys Resolve Si (trade mark) network performance and monitoring software and Hewlett-Packard's Firehunter (trade mark) network service performance monitoring software have sought to capture SLA related information but are limited in several respects as described below.
CrossKeys Resolve Si (trade mark) software seeks to help service providers to manage service performance. Network information is correlated with customer information and quality of service objectives. The software aims to help service providers to ensure that they are delivering high value services that match the needs of customers. Data is retrieved from each end point and link that together make up a delivered service, allowing reports to be generated that illustrate performance issues. In this way the Resolve software helps service providers to compare the service they are providing against those specified in service level agreements. A server is provided which maintains a service level management object model and client workstations run programs termed “Resolve reporter” and “Resolve Configuration” (trade marks). The Reporter software generates pre-configured reports for customers or for the service provider which present information about how the service performance compares with the conditions set out in service level agreements. The reports are distributed by email, by file, on screen or in print. The Resolve Configurator software is a tool for system administrators to control customer, service and contract data. Using this software system administrators are able to create SLAs.
CrossKeys Resolve Si software focuses specifically on fault and performance monitoring. For example, service providers can set up early warnings of SLA violations by using multiple thresholds for Quality of Service (QoS) parameters. If a service is deteriorating, Resolve warns the service provider of impending problems before they impact. Hewlett-Packard's Firehunter (trade mark) software product also provides some capability to capture SLA related information. Firehunter is designed to monitor and report on the delivered quality of Internet services and provides alarms to warn of potential service level agreement violations before they occur. Firehunter software also generates reports that illustrate performance issues for customers.
Both the CrossKeys Resolve software and Hewlett-Packard Firehunter software products are limited in that they do not have the capability to reason over the information presented to them, not meaningfully relate the service requirements from SLAs to the underlying service configuration.
It is accordingly an object of the present invention to provide a method of provisioning a route in a connectionless communications network such that a guaranteed quality of service is provided which overcomes or at least mitigates one or more of the problems noted above.
Another object of the present invention to provide a method of managing service information which overcomes or at least mitigates one or more of the problems noted above.